1. FIELD OF THE INVENTION
This invention relates to fluid flow control valves and more particularly to a multiple disc orifice choke valve.
2. DESCRIPTION OF THE PRIOR ART
Flow restrictor valves utilizing a pair of discs having mating and mismating orifices for controlling the flow rate through the valve are known.
Since flow control disc valves require that the discs be superposed or juxtaposed in the flow passageway with at least one of the discs being angularly rotatable relative to the other, it is necessary that an annular shoulder transversely intersect the flow passageway.
Diametrically opposite apertures or sockets in the shoulder cooperatively receive pins in one disc for preventing angular rotation of the fixed disc relative to the valve body or other disc.
Machine forming such a shoulder in a valve body from valve stock has generally proved unsatisfactory for the reason, in order for the shoulder to adequately support the disc and disc anchoring pins, the bore defining the inner perimeter of the shoulder materially restricts the diameter which may be used through mating and mismating orifices in superposed discs, also materially limiting the otherwise flow capacity of such a valve's fluid passageway.
To compensate for this flow control restriction, it has been the practice to cast the valve body or at least a cage supporting disc in a flow passageway in order to provide a shoulder and a generally oblong aperture through the wall forming the shoulder and defining the inner limit thereof with sufficient space to receive the discs anchoring pins.
However, from an economic standpoint, the cost of casting the valve body or the cage holding the flow control discs adds considerably to the cost of such valves.
My above named application and U.S. Pat. Nos. 4,922,950 and 4,967,787, disclose right angle body valves having cast discs supporting cages interposed in the flow passageway.
This invention is distinctive over the prior art, the valve in the above named application and these patents by providing a machined valve body defining an annular shoulder in the flow passageway having a dual offset bore axial opening therethrough permitting use of discs having orifices approximating valve body flow passageway full capacity.